Swiss pharmaceutical firm Roche this week announced it had developed a test that is 100 per cent accurate at detecting antibodies and 99.8 per cent accurate at ruling out the presence of antibodies in the system. Critically, the accuracy of the test is based on a sample being taken within a fortnight after infection.
Roche has struck a deal with the German government to supply 3 million tests in May and 5 million for each month after that, and is also courting other countries including Australia, the United Kingdom and the United States.
The test samples would be analysed in a hospital or laboratory and take about 18 minutes for a verdict.
Britain’s government had initially ordered millions of finger-prick tests, but the kits produced unreliable results and were never released.
The tests developed by Roche and others that have to be analysed in a laboratory – known as plate-based systems – are now the focus of government attention given they are more accurate.
The unreliability of the finger prick tests mean self-administered antibody tests may never be available in the home. One eventual option may be that a person provides the sample in their own home, but mails it to a hospital or laboratory for a result.
Universities in England and Scotland are also making major progress on antibody testing and could be weeks away from releasing their own versions to compete against major drug companies.
A partnership led by the University of Birmingham has started trials of a new testing kit that might not just detect antibodies through a blood swab, but also the presence of an active COVID-19 infection through a saliva sample.
Professor David Wraith, a professor of immunology and director of the university’s Institute of Immunology and Immunotherapy, told The Sydney Morning Herald and The Age using the same sample to determine an active or recent infection could transform testing regimes.
“A study from Yale University has shown that the [nasal] swabs they currently use for picking up the virus are actually less reliable than looking at saliva alone,” he said. “So this becomes really exciting, that from the same simple sample you could possibly pick up both the virus and antibodies.”
Wraith also said the partnership was conducting a separate trial on people in the Birmingham region who had recently tested positive to COVID-19 to determine how long antibodies remain in their system.
“This will tell us how long the antibodies hang around for. In other words, is the immune response sustained?” he said.
“You hear a lot of stuff from people like the World Health Organisation saying there’s no evidence that immunity is protective. Well actually, the evidence is if someone has antibodies, the likelihood is they will develop less severe disease. So having any immune response, any antibodies, is better than not.”
Asked about immunity on Tuesday, Britain’s chief scientific advisor, Sir Patrick Vallance, told MPs: “The situation at the moment is that an antibody response is likely, most people are likely to be provided some form of immune protection but how much we don’t know. And experience from other coronaviruses suggest it may last for one, two three years but not for many, many years.”
Advice to Downing Street’s Scientific Advisory Group for Emergencies (SAGE) released on Tuesday said antibody testing could be beneficial but warned it may also introduce risky behaviour.
“If a test result is a requirement for a resumption of work, a range of strategies to ‘game’ the system may arise,” the paper warned.
“These include people deliberately seeking out infection or attempting to purchase a fake test result, commercial organisations selling unapproved tests, or approved tests becoming available through private organisations at prices that make them unavailable to most.”
Wraith said the British government had set a “very high bar” for accepting new antibody tests after the initial setback with the reliability of the finger prick tests.
“There was a bit of a rush to buy in anything that looked promising at the beginning, but I think common sense is now prevailing and as the chief medical officer [Chris Whitty] has said, there is nothing worse than a bad test, because it gives you misleading data.”
Bevan Shields is the Europe correspondent for The Sydney Morning Herald and The Age.